May 15, 2018 (Vol. 38, No. 10)
Avoiding Downstream Production Snarls Is an Exercise in Traffic Management
Imagine you’re a biologic molecule moving downstream, passing one bioprocessing “stretch of road” after another, immobilizing here, eluting there, squeezing through resins and membranes, and then, finally, reaching the end of your travels along with your fellow molecules, fully concentrated. If you encountered slowdowns and backups along the way, you might have been as frustrated as a car driver stuck in bumper-to-bumper traffic.
Even if the drug processing road, stretch by stretch, is in good condition, you could encounter stop-and-go traffic, simply because the merest perturbations in flow can slow everything down. You need not suffer delays at any accident scenes or construction sites. If the road is carrying a high enough concentration of biologics—to say nothing of impurities, unwanted cell proteins, leached Protein A, and viruses—waves of congestion can propagate through what should be an unimpeded flow. High-titer-induced slowdowns may be called phantom jams, like their bumper-to-bumper counterparts.
To exorcise phantom jams, suppliers of bioprocessing equipment and consumables are paying more attention to traffic management. They’re incorporating sensors and process control technology; setting up multiple, process-intensifying chromatography routes; upgrading single-use technology; and redefining the rules of the road to support continuous processing.
These innovations promise happier motoring ahead, to judge by recent projections for infrastructure investment. For example, according to Markets and Markets, the global membrane filtration market for pharmaceuticals is expected to reach $6.20 billion by 2021, from a base of $3.55 billion in 2016, reflecting a compound annual growth rate of 11.8%.
Unfortunately, there isn’t a Waze app to show us how biologics traffic is shaping up along any particular route. Instead, one must consult with industry experts. GEN did, and the result is this roundup article. We invite you to ride shotgun.
GEN: What major advances in purification and recovery have occurred over the past 10–15 years?
Dr. Bulpin: The development of platform processes for monoclonal antibody (mAb) production is a significant advance in purification. Within this framework of relatively standard unit operations, we have been able to maximize the productivity of individual unit operations for capture, purification, virus removal, and formulation. This has significantly decreased process development timelines and increased manufacturing efficiency through the commercializing of high-capacity Protein A resins and virus filters, high-selectivity polishing resins, and high-performance ultrafiltration membranes.
Single-use technology is advancing the area of purification. The manufacturing flexibility and reduction in risk make single-use particularly attractive to biomanufacturers. Impact on capital expenditures, cost of goods sold, scaling-out vs. scaling are additional incentives for facilities to be redesigned to support single-use technology.
Finally, we are seeing the need for next-generation processes to meet new market requirements for process flexibility, speed to market, quality, and cost reduction.
Dr. Levison: Over the last decade, we have seen many advances in purification and recovery, including the introduction of higher performing purification tools. Consumables like chromatography adsorbents have much greater productivity, and filtration media offer higher throughput and longer campaign lifetimes than previous versions. On a larger scale, these materials are also now easily integrated into single-use assemblies, helping to streamline processes with minimal connections, and the introduction of novel single-use sensors enables real-time measurement within these newer, more integrated systems.
Ms. Gebski: Major advances center on the implementation of flexible, single-use, and ready-to-use technologies and the improvement in the performance of chromatography resins.
Single-use tangential flow filtration (TFF) cassettes, hollow-fiber filters, and prepacked columns have driven flexibility and efficiency in multiuse facilities. These advances enable reduced setup, cleaning, and changeover times associated with the manufacture of biologics. In addition, recombinant Protein A affinity resins have undergone dramatic improvements: novel ligands, a two-fold increase in dynamic binding capacity, and enhanced flow properties. These improvements have significantly increased the productivity of capture chromatography.
Dr. O’Donnell: A significant advance in downstream processing occurred when the patent for Protein A expired. A plethora of low-cost alternatives are available, some with even better capacity, caustic stability, and adsorption kinetics than the original.
Although the adoption of multicolumn continuous chromatography is slow, most manufacturers and chromatography vendors are invested in this technology. Only time will tell how many columns in series will be the optimal for more efficient purifications.
Disposables are much more common now than they have ever been, including single-use (or more aptly single-campaign) prepacked chromatography columns.
GEN: Which technologies or methods are best suited to the detection, characterization, and con-trol of impurities in biologic products?
Dr. Bulpin: The basic principles of characterization testing of source material followed by batch release testing apply to all manufacturing process, including next-generation processing. Advancing molecular tools such as next-generation sequencing (NGS) and polymerase chain reaction (PCR) are now primed to replace lengthy conventional cell-based assays.
Molecular assays offer the sensitivity and detection range required to confirm a product’s purity, and they can be performed in days as opposed to weeks, making release testing performed in real time a reality. The industry-wide question of “What is a batch?” can be circumvented by designing multiple test points in a process based on a well-thought-out risk assessment strategy.
Dr. Levison: Most recently, we have seen immunoassay technologies that deliver more specific, selective, and sensitive assay results. For example, bio-layer interferometry applies optical analytical techniques to measure biomolecular interactions in real time. Developments in at-line laser capture microdissection technology has enabled the characterization of product-related impurities using LC–MS. Multivariate data analysis has also gained popularity due to its ability to deliver multi-attribute monitoring and identify process perturbations in real time.
Through the Danaher Life Sciences network, Pall Biotech is uniquely positioned with access to the most advanced detection, characterization, and control technologies via the Beckman Coulter Life Sciences, Pall (including Pall ForteBio), and Sciex portfolios.
Ms. Gebski: The control of product- and nonproduct-related impurities in biologic products needs to go as far back as the cell culture process. Fed-batch cell culture processes can starve cells of key nutrients, accumulate deleterious byproducts, and allow cell viability to plummet to less than 80% at harvest. Such changes in culture conditions can impact protein quality and drive impurities into the purification process. By contrast, perfusion cell culture with XCell™ ATF allows a culture to maintain consistent nutrient availability and sustain high cell viability over the entire course of the culture. A consistent cell culture condition drives fewer impurities into the downstream process.
Dr. O’Donnell: Implementation of inline or even online higher order detection methods with real-time analysis enhances the identification and quantitation of impurities. These methods could include multiangle light scattering and Fourier-transform infrared spectroscopy.
The acceptance of sub-2-micron chromatography particles in liquid chromatography (LC) and liquid chromatography–mass spectrometry (LC–MS) analysis enables rapid and almost limitless characterization of impurities. However, limitless identification and characterization might reveal an impurity that hadn’t been present before, or that hadn’t been identified even though it had been present before.
GEN: What are the major challenges in implementing a continuous process in downstream operations?
Dr. Bulpin: Process intensification, the forerunner of continuous manufacturing, is already having significant impact of cost of goods sold (COGS) where it is being implemented. For instance, one customer reported a 75% reduction in COGS. COGS will continue to fall as we operate our process in connect and continuous modes. The key business risk, however, will be clearing regulatory hurdles as processes look less like a series of sequential operations and more like an automated assembly line. Delays in product approvals have a major impact on revenue and market position driving a risk-averse culture.
We, as suppliers, biomanufacturers, and regulators, must work together to build the regulatory framework for approval of next-generation processes. MilliporeSigma continues to collaborate with drug manufacturers, as well as other single-use suppliers, to standardize test methods for single-use systems and to ease the implementation and regulatory filing challenges associated with continuous manufacturing.
Dr. Levison: We see that the major hurdle here is unfamiliarity and lack of trust, so for the last few years, the message at Pall Biotech has been clear: Contrary to widespread belief, there are minimal challenges in the adoption of fully continuous or semicontinuous processes.
There is nothing that is more difficult or costly to implement than traditional technologies. The [new] processes even use the same buffers, filtration media, and chromatography adsorbents—just more efficiently. And the same technologies are used, just in a different configuration.
Ms. Gebski: More efficient seed-train expansion and upstream continuous processing are challenges that are being met with high-performance cell retention systems such as KrosFlo® TFF and XCell™ ATF. Perfusion cell culture delivers a harvest feedstream ready for purification, thus effectively linking upstream and downstream operations, the first step in continuous processing.
Challenges in implementing downstream continuous processes center on the connection and automation control of multiple unit operations. Individual unit operations, from multiple chromatography steps to viral filtration, must be transitioned from batch to continuous, and then multiple, optimized continuous unit operations must be linked to derive a fully continuous downstream process.
A significant amount of process development and automation layered on top is required as compared to standard batch processing, but advanced bioprocessing companies will make hybrid-continuous and fully continuous processing a reality in the next five years, as advances in system integration and control functionality enable the linking of technologies.
Dr. O’Donnell: A major challenge in continuous downstream processing is marrying complex equipment with the design of single-use technologies. What happens when a valve, detector cell, or pump head in a very complex method fails? Does the whole process result in a failed manufacturer lot? The aversion to increased risk will supersede efficiency, particularly when the process purifies a particularly high-value product. In addition, the training of manufacturing personnel to properly operate and monitor complex processes will always be a major concern.
GEN: What has been your company’s approach to solving the downstream bottleneck issue?
Dr. Bulpin: An evolutionary approach must be taken toward integrated and continuous processes. Process intensification, like multicolumn chromatography or the implementation of single-pass TFF, has been a successful first step. We are now in the process of connecting operations such as anion exchange and virus filtration into a single operation.
Based on this learning, MilliporeSigma will develop software and automation capabilities that don’t yet exist to fully connect and integrate both upstream and downstream processes to enable continuous processing. Software must enable processing systems to communicate and integrate several operations to maintain process controls and product quality. Sensors and process analytical technology strategy are needed to drive control and automation decisions.
Biomanufacturers are clamoring for this type of software and control platform, and we are moving swiftly to deliver it. Next-generation processing is a key strategic focus area for us, and we are committed to leading the industry in this processing evolution. For decades, MilliporeSigma has collaborated with our customers to shape drug production processes, and it will continue to do so.
Dr. Levison: Our products and services can be tailored to support traditional, single-use, continuous, semicontinuous, and hybrid drug manufacturing needs. From a services perspective, we support production from early-phase development to commercial manufacturing. And from a technology perspective, working independently or as a member of the Danaher Life Sciences network, we develop tools that deliver all the right resources for lifetime solutions.
We want to deliver efficient, flexible options, and we have no desire to push customers in any one specific direction. Whether we are providing one consumable or piece of equipment, or a full lineup of Pall Biotech products, we simply want to meet every customer’s needs.
Ms. Gebski: Downstream bottlenecks can be resolved by improving or reducing process steps. Repligen technologies are available in single-use and ready-to-use formats that enable more efficient downstream processing. SIUS® TFF cassettes are purpose-built, single-use cassettes that eliminate the need for post-use cleaning, testing, and storage, ultimately reducing buffer usage and the labor required for support. ProConnex® hollow-fiber flow paths are supplied gamma-irradiated and fully assembled, enabling expedited setup and reduced manufacturing downtime.
OPUS® prepacked columns are the most configurable and platformable prepacked columns in the bioprocess industry, with diameters ranging from 0.5 to 80 cm. OPUS columns enable time savings, cost savings, and reproducibility in downstream processing, thus reducing process development cycles, time to clinic, and overall cost to manufacture. With configurability for shorter bed heights and matched pressure-flow performance across multiple columns, OPUS columns are well suited for multicolumn chromatography applications, thus also enabling continuous downstream processing.
Dr. O’Donnell: Tosoh Bioscience, with its full line of process resins, can manufacture chromatographic resins with varying pore and particle sizes. By optimizing chromatographic resins with enhanced kinetic performance, multicolumn continuous chromatography can be accomplished with smaller columns and with potentially decreased complexity. This will decrease the cost of production, reduce risk in some cases, and facilitate better training of manufacturing personnel.